Motorized fan unit for a motor vehicle

ABSTRACT

The invention relates to a motorized fan unit for a motor vehicle, comprising a motor (2), a fan (3) for moving an air flow (F) that is configured to be controlled by the motor (2), and a control module (4) for controlling said motor (2), the control module (4) comprising an electronic card, the motorized fan unit delimiting a main air-flow circulation duct (5) and a cooling duct (6) configured to cool said electronic card of the control module, the duct (6) comprising an inlet (7) provided with a deflector (8) for diverting a portion of the air flow into the duct (6), the deflector (8) being mounted movably according to an air flow rate in the main duct for the purpose of increasing an air flow rate in the cooling duct (6) with the speed of the air flow in the main duct (5).

The subject matter of the invention is a motorized fan unit for a motor vehicle.

As a preference, such a motorized fan unit forms part of a heating, ventilation and/or air conditioning device of the motor vehicle, which regulates the temperature of an air flow intended to supply the interior of the vehicle.

The motorized fan unit, for its part, serves to make the air flow enter and circulate in the heating, ventilation and/or air conditioning device as far as outlet openings, where the air enters the vehicle interior.

The motorized fan unit in the known way comprises an electric motor, for example with brushes, on which an impeller is mounted to cause the air to move, and a device for controlling the electric motor, the electric motor control device comprising an electronic board.

In general, the motorized fan unit is equipped with a duct for the cooling of the motor. The electronic board is cooled in the main flow so as to avoid excessive heating of the electronic components borne by the electronic board.

Nevertheless, depending on the conditions of use of the motorized fan unit, the cooling provided by this configuration of the prior art leads to a drop in pressure in the main air flow and at constant flow rate leads to an increase in the intensity of noise, which may then impair the performance of the motorized fan unit.

It is an object of the invention to improve this situation.

To that end, the subject matter of the invention is a motorized fan unit for motor vehicle, comprising a motor, a fan for setting in motion an air flow and configured to be controlled by the motor, and a control module for controlling said motor, the control module comprising an electronic board, the motorized fan unit delimiting a first circulation duct for the air flow set in motion by the fan, referred to as the main duct, and a secondary air flow duct, referred to as cooling duct, configured to cool said electronic board of the control module, the cooling duct comprising an inlet equipped with a deflector for diverting part of the air flow set in motion by the fan into the cooling duct, the deflector being mounted with the ability to move according to a flow rate of air in the main duct in a direction for increasing the flow rate of air in the cooling duct with a velocity of the air flow in the main duct.

By virtue of the present invention, the flow rate of air in the cooling duct is adjusted according to the heat-dissipation requirements of the motorized fan unit, thereby ensuring sufficient cooling of the electronic board of the motorized fan unit in all circumstances.

According to another feature of the invention, a gradient along which the flow rate of air in the cooling duct increases as a function of the velocity of the air flow in the main duct is a strictly increasing gradient.

According to another feature of the invention, the deflector is positioned in the main duct, outside of the cooling duct.

According to another feature of the invention, the deflector is mounted with the ability to pivot.

According to another feature of the invention, an axis of pivoting of the deflector extends in a direction substantially orthogonal to a main direction of the air flow in the main air duct at the deflector.

According to another feature of the invention, the axis of pivoting of the deflector extends in a radial direction of the motorized fan unit.

According to another feature of the invention, the deflector comprises a curved deflection surface.

According to another feature of the invention, a radius of curvature of the deflection surface is such that a center of an associated osculating circle is positioned upstream of the deflector relative to the flow of the air in the main air duct.

According to another feature of the invention, the deflector is made from a flexible material.

According to another feature of the invention, the flexible material is an HPPE polymer.

According to another feature of the invention, the deflector is obtained by molding.

According to another feature of the invention, the motorized fan unit comprises at least one low wall extending in the main duct and bordering the inlet to the cooling duct.

According to another feature of the invention, the cooling duct is configured to also cool the motor.

Another subject of the invention is a heating, ventilation and/or air conditioning device for a motor vehicle, comprising a motorized fan unit as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics, details and advantages of the invention will become apparent upon reading the detailed description below, and upon analyzing the appended drawings, in which:

FIG. 1 is a perspective view of a motorized fan unit according to the present invention;

FIG. 2 is another perspective view of the motorized fan unit of FIG. 1;

FIG. 3 is a partial schematic view of the motorized fan unit of FIG. 1 (with a fan being omitted);

FIG. 4 is a schematic curve of an air flow rate in a cooling duct of the motorized fan unit of FIG. 1 as a function of a velocity of a flow of air in the motorized fan unit.

DESCRIPTION OF EMBODIMENTS

A subject of the invention is a motorized fan unit for a motor vehicle, referenced 1 in the figures.

The motorized fan unit preferably forms part of a heating, ventilation and/or air conditioning device of the motor vehicle.

As visible in FIGS. 1 and 2, the motorized fan unit 1 comprises a motor 2, a fan 3 and a control module 4 for controlling the motor 2.

The fan 3 is controlled by the motor 2 and sets an air flow F in motion. In FIGS. 1 and 2, the fan 3 takes the form of an impeller wheel.

The control module 4 comprises an electronic board equipped with electronic components that it is necessary to cool in order to avoid any malfunctioning of the motorized fan unit.

As illustrated in FIGS. 1 and 2, the motorized fan unit 1 delimits two air circulation ducts: a first duct, referred to as the main duct, referenced 5, and a second duct, referred to as the cooling duct, referenced 6.

Thus, the air flow F is split into a main air flow F1 circulating in the duct 5, and a cooling air flow F2 circulating in the duct 6.

As is evident from FIGS. 1 to 3, the cooling duct 6 is configured to cool the control module 4 and, in particular, the electronic board thereof. Note that the electronic board may potentially be fitted with a heat sink that the flow F2 cools.

As is also evident from FIGS. 1 to 3, the duct 6 comprises an inlet 7 equipped with a deflector 8 to divert part of the air flow F (the flow F2) into the cooling duct 6. In the example depicted, the air inlet 7 extends in a plane substantially perpendicular to the axis of rotation of the electric motor 2.

In other words, the cooling duct 6 constitutes a tapping off of the main duct 5. Stated differently, the cooling duct 6 branches off the main duct 5.

Thus, the air flow F2 flows around the control module, the electronic board and/or the heat sink, then circulates to the center of the motor and re-emerges via the impeller wheel 3. Note that the duct 6 also provides cooling of the motor 2.

As visible in FIG. 2, the inlet 7 is an orifice bordered by a low boundary wall 9 into or beneath which the deflector 8 is inserted.

The deflector 8 is mounted with the ability to move according to a flow rate D(F2) of air in the cooling duct 6 in a direction of increasing a flow rate D(F2) of air in the cooling duct 6 with a velocity v(F) of the air flow F in the main duct (upstream of the cooling duct 6), as will be detailed in connection with FIG. 4.

As a preference, a gradient along which the flow rate of air in the cooling duct increases as a function of the velocity of the air flow in the main duct is a strictly increasing gradient. In FIG. 4, the curve of the flow rate of air in the cooling duct as a function of the velocity of the air flow in the main duct is of substantially parabolic shape, as will be detailed later.

As is visible in FIGS. 1 to 3, the deflector 8 is positioned in the main duct 5, outside of the cooling duct 6. This configuration provides a simple way of bleeding the air flow F2 off from the duct 5.

In the embodiment illustrated, the deflector 8 is mounted with the ability to pivot, an axis of pivoting P of the deflector 8 extending in a direction substantially orthogonal to a main direction of the air flow F1 in the main air duct 5 at the deflector 8. In other words, the axis of pivoting P extends in a radial direction. This configuration ensures that the air flow F2 enters the cooling duct 6 without turbulence. The axis of pivoting P passes through the point C schematically indicating the position of the axis of rotation of the electric motor 2 in FIG. 3.

As is particularly visible in FIGS. 1 and 2, the deflector 8 comprises a deflection surface 10 via which the air flow F2 is diverted into the inlet 7 of the cooling duct 6.

The deflection surface 10 is curved and extends from the axis of pivoting P into the duct 5.

As is also evident from the figures, the radius of curvature of the surface 10 is such that the center of the osculating circle is positioned upstream of the deflector 8 relative to the flow of the air.

The dimensions of the surface 10 are chosen according to the power of the control module 4.

As a preference, the deflector 8, and particularly the deflection surface 10, is made from a flexible material, notably an HPPE polymer or SEBS, so as to ensure that the flow rate of air in the duct 6 adjusts according to the velocity of the air flow F.

Advantageously, the deflector 8 is obtained by molding or overmolding.

The flexibility of the deflector 8 ensures that the flow rate of air F2 in the duct 6 increases with the velocity of the air F. Simulations performed by the Applicant have demonstrated that the flow rate (denoted D in FIG. 4) of air in the duct 6 is a substantially parabolic function of the velocity (denoted v in FIG. 4) in the duct 5 upstream of the inlet 7.

At low velocity, the deflection surface 10 has a tendency to lie close to the inlet 7 and only a small proportion of the air flow F is diverted into the duct 6. The flow rate D in the duct 6 is therefore low. In other words, the deflection surface 10 opens the inlet 7 only very little.

In addition, because the surface 10 it extends in the plane of the inlet 7 at low velocity, the apparent surface area (namely that portion of the surface 10 that fronts onto the air flow F) exhibited by the deflector 8 is low, thereby improving the aeraulics and the acoustics of the motorized fan unit.

When the velocity increases, for example at around 10 to 15 m/s, the deflection surface 10 lifts, and this increases the apparent surface area of the deflector in the air flow. In consequence, the flow rate D of the air flow F2 in the duct 6 increases. The position of the deflector 8 changes progressively with the increase in the velocity of the air flow F.

According to one embodiment which has not been depicted, the deflector 8 is bordered by a low wall extending in a plane perpendicular to the plane of the air inlet 7 and also perpendicular to the axis of pivoting P visible in FIG. 3. The low wall is situated radially on the side of the inlet 7 that is furthest from the electric motor 2. The low wall is able to limit the extent to which air escapes between the lateral edge of the deflector 8 and the edge of the air inlet 7. According to a variant, likewise not depicted, the deflector 8 comprises a vertical portion bordering the lateral edge of the deflector and perpendicular to the deflection surface 10. This vertical portion performs a similar role to the low wall and thus is able to limit the extent to which air escapes between the deflector 8 and the edge of the air inlet 7.

The substantially parabolic behavior of the flow rate D is particularly beneficial insofar as the heat dissipation requirements of the control module and of the motor themselves likewise vary in that same way. By contrast, the solutions known from the prior art propose a flow rate that at best varies as a linear function of the velocity of the air flow F, and this increases the pressure drop at nominal velocity. At maximum velocity, the deflector 8 offers the same apparent surface area as the linear solution. Below the maximum velocity, the deflector offers a surface area that is smaller than that of the known, fixed-geometry, solutions.

Thus, as is evident from the foregoing description, the deflector 8 represents a simple-to-implement and effective means for cooling the control module and the motor of the motorized fan unit. 

1. A motorized fan unit for motor vehicle, comprising: a motor; a fan for setting in motion an air flow and configured to be controlled by the motor; and a control module for controlling said motor comprising an electronic board, the motorized fan unit delimiting a first circulation duct for the air flow set in motion by the fan, referred to as the main duct, and a secondary air flow duct, referred to as cooling duct, configured to cool said electronic board of the control module, the cooling duct comprising an inlet equipped with a deflector for diverting part of the air flow set in motion by the fan into the cooling duct, the deflector being mounted with the ability to move according to a flow rate of air in the main duct in a direction for increasing a flow rate of air in the cooling duct with a velocity of the air flow in the main duct.
 2. The motorized fan unit as claimed in claim 1, wherein a gradient along which the flow rate of air in the cooling duct increases as a function of the velocity of the air flow in the main duct is a strictly increasing gradient.
 3. The motorized fan unit as claimed in claim 1, wherein the deflector is positioned in the main duct, outside of the cooling duct.
 4. The motorized fan unit as claimed in claim 1, wherein the deflector is mounted with the ability to pivot.
 5. The motorized fan unit as claimed in claim 4, wherein the axis of pivoting of the deflector extends in a radial direction of the motorized fan unit.
 6. The motorized fan unit as claimed in claim 1, wherein the deflector comprises a curved deflection surface.
 7. The motorized fan unit as claimed in claim 1, wherein the deflector is made from a flexible material, notably an HPPE polymer.
 8. The motorized fan unit as claimed in claim 1, comprising at least one low wall extending in the main duct and bordering the inlet to the cooling duct.
 9. The motorized fan unit as claimed in claim 1, wherein the cooling duct is configured to also cool the motor.
 10. A heating, ventilation and/or air conditioning device for a motor vehicle, comprising a motorized fan unit as claimed in claim
 1. 